Replacement Channels

ABSTRACT

The present disclosure relates to a device and method for strain inducing or high mobility channel replacement in a semiconductor device. The semiconductor device is configured to control current from a source to a drain through a channel region by use of a gate. A strain inducing or high mobility layer produced in the channel region between the source and drain can result in better device performance compared to Si, faster devices, faster data transmission, and is fully compatible with the current semiconductor manufacturing infrastructure.

BACKGROUND

The cost and complexity associated with scaling of semiconductor devicesizes according to Moore's law has given rise to new methods to improvesemiconductor device characteristics. New gate materials such as Hi-Kmetal gates to decrease device leakage, finFET devices with increasedeffective gate area as compared to same-size planar devices, and straininducing channels for increased charge carrier mobility are a fewexamples of methods to continue Moore's Law scaling for next generationmicroprocessor designs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates semiconductor devices with strain inducing channelsformed by conventional methods.

FIG. 2 illustrates some embodiments of strained lattices.

FIG. 3 a-FIG. 3 c illustrate some embodiments of forming a p-typemetal-oxide semiconductor field transistor (p-MOS) transistor with apartial replacement channel.

FIG. 4 a-FIG. 4 c illustrate some embodiments of forming a p-typemetal-oxide semiconductor field transistor (p-MOS) transistor with afull replacement channel.

FIG. 5 a illustrates some embodiments of forming a partial replacementchannel on planar FETs.

FIG. 5 b illustrates some embodiments of forming a partial replacementchannel on finFETs.

FIG. 6 a illustrates some embodiments of forming a full replacementchannel on planar FETs.

FIG. 6 b illustrates some embodiments of forming a full replacementchannel on finFETs.

FIG. 7 a-FIG. 7 e illustrate some detailed embodiments of forming achannel-last replacement channel on a planar FET in a Hi-K metal gatelast (HKL) flow.

FIG. 8 a-FIG. 8 d illustrate some embodiments of forming a channel-lastreplacement channel on planar FETs in a Hi-K metal gate last (HKL) flow.

FIG. 9 a-FIG. 9 d illustrate some embodiments of forming a channel-lastreplacement channel on finFETs in a Hi-K metal gate last (HKL) flow.

FIG. 10 a-FIG. 10 e illustrate cross-sectional views of some embodimentsof typical SSD etch profiles.

FIG. 11 illustrates a comparison of some embodiments of a p-MOS formedby conventional strain inducing channel methods vs. a p-MOS formed by afull replacement channel method.

FIG. 12 illustrates a flow diagram of some embodiments of a conventionalmethod for manufacturing a strain inducing or high mobility channel.

FIG. 13 illustrates a flow diagram of some embodiments of a method formanufacturing a replacement channel that can be used for both a partialreplacement channel and a full replacement channel.

FIG. 14 illustrates a flow diagram of some embodiments of a method formanufacturing a channel-last replacement channel.

FIG. 15 a-FIG. 15 f illustrate cross-sectional views of some embodimentsof channel-last replacement channel profiles.

DETAILED DESCRIPTION

The description herein is made with reference to the drawings, whereinlike reference numerals are generally utilized to refer to like elementsthroughout, and wherein the various structures are not necessarily drawnto scale. In the following description, for purposes of explanation,numerous specific details are set forth in order to facilitateunderstanding. It may be evident, however, to one of ordinary skill inthe art, that one or more aspects described herein may be practiced witha lesser degree of these specific details. In other instances, knownstructures and devices are shown in block diagram form to facilitateunderstanding.

FIG. 1 illustrates semiconductor devices with strain inducing channelsformed by conventional methods, comprising an arrangement 100 a of twoplanar field-effect transistors (FETs) 102 a and 102 b, as well as anarrangement 100 b of four fin field-effect transistors (finFETs) 104a-104 d. Each FET 102 a-102 b and finFET 104 a-104 d comprise threeterminals: a source 106, a drain 108, and a gate 110, and are formed ona silicon (Si) substrate 112 and isolated by shallow trench isolation(STI) channels 114 filled with a dielectric material (e.g., SiO₂).Planar FETs 102 a-102 b and finFETs 104 a-104 d typically comprises ametal-oxide-semiconductor FETs (MOSFETs) wherein a Hi-K dielectricresides between the gate 110 and a channel region 116 formed betweeneach source 106 and drain 108 to reduce power loss due to gate currentleakage into the channel region 116.

One factor in determining the performance of a FET is the mobility ofcharge carriers through the channel region 116. To increase the mobilityof charge carriers in a FET, a strain inducing channel may be produced.However, strain inducing channels formed by conventional methods areformed early in semiconductor processing, and may be subject to a seriesof thermal processing steps which can degrade their crystal structureand hence reduce their charge carrier mobility.

Accordingly, the present disclosure relates to a device and method forstrain inducing or high mobility channel replacement in a semiconductordevice. A sacrificial layer is formed early in the semiconductor deviceprocessing. After one or more thermal processing steps are carried outwith the sacrificial layer in place, the sacrificial layer is removed toform a recess. A strain inducing or high mobility layer then fills therecess to insure a robust crystal structure with minimal defects. Straininducing or high mobility channel replacement may result in betterdevice performance compared to conventional techniques for straininducing channel formation, and is fully compatible with the currentsemiconductor manufacturing infrastructure.

FIG. 2 illustrates some embodiments of strained lattices 200 which areused in semiconductor devices due to their relatively high chargecarrier mobility. The strained lattices 200 comprise a first lattice 202composed of species A 204, a second lattice 206 composed of species B208, and a third lattice 210 composed of species C 212. The periodicspacing of a species within a given lattice is defined as its latticeconstant. The first lattice 202 has a lattice constant x 214, the secondlattice 206 has a lattice constant y 216, and the third lattice 210 hasa lattice constant z 218. Near the interface region 222 of the firstlattice 202 and the second lattice 206 a mismatch in lattice constantsresults in a strain of one or more of the first or second crystallattices, 202 and 206 respectively. In this embodiment, the secondlattice 206 is subject to a compressive strain 224 resulting a mismatchof its lattice constant y with the lattice constant x 214 (i.e., y>xresults in compressive 224 strain for the second lattice 206).Similarly, the third lattice 210 is subject to a tensile strain 226resulting from a mismatch of its lattice constant z with the latticeconstant x 214 near the interface 228 (i.e., z<x results in tensilestrain 226 for the third lattice 210).

Mechanical strain, thermal effects, and chemical effects are someexamples of factors that can result in defects within a lattice. Avacancy 230 results from a particle of species A 204 being absent fromits expected periodic location. An Interstitial 232 results from aparticle of species A 204 being in a location other than its expectedperiodic location. A substitution 234 results from a particle of speciesC 212 residing in a location where a particle of species A 204 isexpected (e.g., a contaminant for a single-species lattice). An edgedislocation 236 is where an extra half plane of particles is introduced.A stacking fault 238 occurs when one or more planes of atoms interruptsthe normal periodic stacking of particle planes. These defects degradethe crystal structure and hence the charge carrier mobility of thesestrained lattices. Moreover, as defects accumulate the crystal structuremay become so distorted that it becomes amorphous.

To improve the strain within a strain inducing layer when thermalprocessing steps are used in semiconductor device processing asacrificial layer may be formed early in the semiconductor deviceprocessing. After one or more thermal processing steps are carried outwith the sacrificial layer in place, the sacrificial layer is removed toform a recess. A strain inducing or high mobility layer then fills therecess to insure a robust crystal structure with minimal defects.

FIG. 3 a-FIG. 3 c illustrate some embodiments of forming a p-typemetal-oxide semiconductor field transistor (p-MOS) transistor with apartial replacement channel. FIG. 3 a illustrates p-MOS 300 comprising asource 302, a drain 304, and a gate 306. The gate 306 comprises a hardmask 308, Poly-Silicon gate material (Poly-Si) 310, a gate dielectric312, and sidewall spacers 314 to insure electrical isolation of the gate306 from the source 302 and drain 304. The p-MOS 300 is situated on a Sisubstrate 316 (i.e., Si lattice) to which a sacrificial layer of Si orSiGe 318 has been added (i.e., SiGex where x≧0.2). The sacrificial layerof Si or SiGe 318 forms a channel region 320 through which hole chargecarriers 324 move from the source 302 to the drain 304. The mismatch inlattice constants between the Si substrate 314 and combined Si or SiGelayer 318 results in a compressive strain within the channel region 320of the p-MOS 300 along the channel width direction, having the effect ofincreasing the hole charge carrier 322 mobility by approximately 1.4-1.8times that of bulk devices (i.e., Si).

The hole charge carrier 322 mobility, however, will be degraded bythermal processing steps that occur after the formation of thesacrificial layer of Si or SiGe 318, due to the distortion its latticestructure. FIG. 3 b illustrates the p-MOS 300 wherein the sacrificial Sior SiGe layer 318 has been etched away (e.g., a wet chemical etch, a drychemical etch, or a combination thereof) to form a recess 324 after thethermal processing steps are complete. At the same time (i.e., as a partof the same etch step) a strained source drain (SSD) etch forms largeretch profile regions 326 within the recess. Note that a portion of thesacrificial layer of Si or SiGe 318 approximately 1-50 nm thick remainsbelow the gate 306, and shields the gate 306 from any undesired effectsfrom removing the sacrificial layer of Si or SiGe 318 (e.g., damageand/or contamination).

FIG. 3 c illustrates the p-MOS 300 wherein the recess 324 has beenfilled with a single strain inducing or high mobility layer 330 (i.e.,single lattice) comprising SiGex (where x≧0.2) or Ge with a gradientconcentration, either doped or undoped, with a cap formed from thesacrificial layer of Si or SiGe 318 that remains below the gate 306.This method of replacement results in a partial replacement channel 332and source drain regions 328 comprising a single crystal. Whileformation of a partial replacement channel 332 has the benefit ofprotecting the gate 306, it results in less overall strain and henceless hole mobility than a full replacement channel. Nonetheless, becausethe partial replacement channel 332 comprises a strain induced layerformed after thermal processing, it has an increased induced-strainrelative to conventional devices.

A strain inducing channel on an n-type metal-oxide semiconductor fieldtransistor (n-MOS) can be achieved by the same means as described in theembodiments of the p-MOS 300 wherein a composite layer of strained Si onstrained SiGe (e.g., Si/SiGe_(0.2)) fills the recess 324 instead of thestrain inducing or high mobility layer 330. The mismatch in latticeconstants between the composite layer of strained Si on strained SiGeand the substrate 314 results in a tensile strain of the n-MOS along thechannel width direction, having the effect of increasing the electroncharge carrier mobility by approximately 1.25-2 times that of bulkdevices.

FIG. 4 a-FIG. 4 c illustrate some embodiments of forming a p-typemetal-oxide semiconductor field transistor (p-MOS) transistor with afull replacement channel. The formation of a full replacement channelillustrated for a p-MOS 400 in FIG. 4 a-4 c is similar to the formationof the partial replacement channel described in the embodiments of FIG.3 a-FIG. 3 c. However, for the formation of a full replacement channel,no portion of the sacrificial layer of Si or SiGe 318 remains such thatthe recess 324 abuts the bottom of the gate dielectric 312. The recess324 is then filled with a single strain inducing or high mobility layer430 (i.e., single lattice) comprising SiGex (where x≧0.2) or Ge with agradient concentration, and is either doped or undoped. Note that no capis formed since the sacrificial layer of Si or SiGe 318 has beencompletely removed. The strain inducing or high mobility layer 430 formsthe source 302, drain 304, and a full replacement channel 432, whichresults in more overall strain than the partial replacement channel, andhence an increased hole mobility relative to the partial replacementchannel.

FIG. 5 a illustrates some embodiments of forming a partial replacementchannel on planar FETs 500 a. Note that the cross-section shown for thisembodiment is rotated 90 degrees from the embodiments of FIG. 3 and FIG.4 such that the channel length direction faces out of the page. Theplanar FETs 500 a comprise a gate 502 a, and Si or SiGex channels 504 awhich are isolated from one another by a shallow trench isolation oxide(STI OX) 506 a. Each original channel of Si or SiGe is etched away(e.g., a wet chemical etch, a dry chemical etch, or a combinationthereof) to form a recess 508 a, leaving a portion of the Si or SiGechannel 510 a approximately 1-50 nm thick below the gate 502 a. A straininducing layer or high mobility layer 512 a of SiGex (where x≧0.2) or Geis then re-grown within the recess 508 a (e.g., epitaxial growth). Thismethod results in the formation of a partial replacement channel on theplanar FETs 500 a.

FIG. 5 b illustrates some embodiments of forming a partial replacementchannel on finFETs 500 b, which is identical to the embodiments offorming a partial replacement channel on planar FETs 500 a with thedistinction that the Si or SiGex channels 504 b extend into the gate 502b to form “fins” 507 b that are wrapped in by the gate 502 b on threesides. Each Si or SiGex channel 504 b is etched away to form a recess508 b with a portion of the Si or SiGe channel 510 b approximately 1-50nm thick remaining at the top of the original channel 504 b. A straininducing layer or high mobility layer 512 b of SiGex (where x≧0.2) or Geis then re-grown within the recess 508 b. This method results in theformation of a partial replacement channel on the finFETs 500 b.

FIG. 6 a illustrates some embodiments of forming a full replacementchannel on planar FETs 600 a, which comprise a gate 602 a, and Si orSiGex channels 604 a which are isolated from one another by a shallowtrench isolation oxide (STI OX) 606 a. Each original channel of Si orSiGe is etched away to form a recess 608 a such that no portion of theSi or SiGe channel 604 a resides between the recess 608 a and the gate602 a (i.e., the recess abuts the bottom of the gate). A strain inducinglayer or high mobility layer 610 a of SiGex (where x≧0.2) or Ge is thenre-grown within the recess 608 a. This method results in the formationof a full replacement channel on the planar FETs 600 a.

FIG. 6 b illustrates some embodiments of forming a full replacementchannel on finFETs 600 b. The distinction between the embodiments of 600a and 600 b is similar to the distinction between the embodiments of 500a and 500 b, wherein the only difference is that the Si or SiGexchannels 604 b extend into the gate 602 b to form “fins” 607 b that arewrapped in by the gate 602 b on three sides. Each Si or SiGe channel isetched away to form a recess 608 b which abuts the bottom of the gate602 b. A strain inducing layer or high mobility layer 610 b of SiGex(where x≧0.2) or Ge is then re-grown within the recess 608 b to form afull replacement channel on the finFETs 600 b.

FIG. 7 a-FIG. 7 e illustrate some detailed embodiments of forming achannel-last replacement channel on a planar FET 700 in a Hi-K metalgate last (HKL) flow. In the Hi-K metal gate last flow a dummy poly gateand dummy liner (IL) are formed early in the semiconductor deviceprocessing and then replaced with a real gate late in the processing. Incontrast, a Hi-K metal gate first (HKF) flow forms the real gate earlyin the processing.

FIG. 7 a illustrates a cross-sectional view of a planar FET 700comprising a dummy gate 702, a dummy liner (IL) 704, a Si or SiGex(where x≧0.2) channel 706, a spacer 708, and a contact etch stop layer710 formed between the dummy gate 702 and spacer 708 and an interlayerdielectric (ILD) 712. FIG. 7 b illustrates a cross-sectional view of theplanar FET 700 wherein a chemical-mechanical polish (CMP) 714 hasremoved the contact etch stop layer 710 and ILD 712 to expose the top ofthe dummy gate 702. FIG. 7 c illustrates a cross-sectional view of theplanar FET 700 wherein the dummy gate 702 and a dummy IL 704 have beenetched away to form a first recess 716. FIG. 7 d illustrates across-sectional view of the planar FET 700 wherein the Si or SiGexchannel 706 has been etched away to form a second recess 718. FIG. 7 eillustrates a cross-sectional view of the planar FET 700 wherein astrain inducing layer or high mobility layer 720 of SiGex (where x≧0.2)or Ge is re-grown within the second recess 718 to form a channel-lastreplacement channel.

FIG. 8 a-FIG. 8 d illustrate some embodiments of forming a channel-lastreplacement channel on planar FETs 800 in a Hi-K metal gate last (HKL)flow. FIG. 8 a illustrates a cross-sectional view of the planar FETs800, which comprise a dummy gate 802, and Si or SiGex channels 804 whichare isolated from one another by a shallow trench isolation oxide (STIOX) 806. FIG. 8 b illustrates a cross-sectional view of the planar FET800 wherein the dummy gate 802 has been etched away. FIG. 8 cillustrates a cross-sectional view of the planar FET 800 wherein eachoriginal Si or SiGe channel 804 is etched away to form a recess 808.FIG. 8 d illustrates a cross-sectional view of the planar FET 800wherein a strain inducing layer or high mobility layer 810 of SiGex(where x≧0.2) or Ge is then re-grown within the recess 808 to form achannel-last replacement channel.

FIG. 9 a-FIG. 9 d illustrate some embodiments of forming a channel-lastreplacement channel on finFETs 900 in a Hi-K metal gate last (HKL) flow.The distinction between the embodiments of FIG. 8 a-FIG. 8 d and FIG. 9a-FIG. 9 d is similar to the distinction between the previousembodiments of 600 a and 600 b wherein the only difference is that theSi or SiGex channels 904 extend into the gate dummy gate 902 to form“fins” 908 as illustrated in a cross-sectional view in FIG. 9 a. FIG. 9b illustrates a cross-sectional view of the finFET 900 wherein the dummygate 902 has been etched away to expose the Si or SiGex “fins” 908. FIG.9 c illustrates a cross-sectional view of the planar FET 900 whereineach original Si or SiGe channel 904 is etched away to form a recess910. FIG. 9 d illustrates a cross-sectional view of the planar FET 900wherein a strain inducing layer or high mobility layer 912 of SiGex(where x≧0.2) or Ge is then re-grown within the recess 910 to form achannel-last replacement channel.

FIG. 10 a-FIG. 10 e illustrate cross-sectional views of some embodimentsof typical SSD etch profiles. FIG. 10 a illustrates a cross-sectionalview of some embodiments 1000 a of a sigma-shape etch profile 1002 a fora strained source drain (SSD) etch. FIG. 10 b illustrates across-sectional view of some embodiments 1000 b of a sigma-shape etchprofile 1002 b for a strained source drain (SSD) etch. FIG. 10 cillustrates a cross-sectional view of some embodiments 1000 c of ananisotropic etch profile 1002 c for a strained source drain (SSD) etch.FIG. 10 d illustrates a cross-sectional view of some embodiments 1000 dof an isotropic etch profile 1002 d for a strained source drain (SSD)etch. FIG. 10 e illustrates a cross-sectional view of some embodiments1000 e of a triangular etch profile 1002 e for a strained source drain(SSD) etch.

FIG. 11 illustrates a comparison of some embodiments of a p-MOS 1100 aformed by conventional strain inducing channel methods vs. a p-MOS 1100b formed by a full replacement channel method. The p-MOS 1100 a formedby a conventional methods comprises a source 1102 a and drain 1104 acomprising first and second strained EPI layers of SiGe, respectively.The p-MOS 1100 a further comprises gate 1106 a, and a third strainedlayer of SiGe 1108 that forms a channel region 1110 a. A first boundary1112 a separates the first strained EPI layer of SiGe of the source 1102a from the third strained layer of SiGe 1108. A second boundary 1114 aseparates the second strained EPI layer of SiGe of the drain 1104 a fromthe third strained layer of SiGe 1108. The shape of the first and secondboundaries 1112 a and 1114 a is determined by the type of strainedsource drain (SSD) etch used to form the source 1102 a and drain 1104 a,and may comprise a sigma-shape profile (shown), an anisotropic etchprofile, or an isotropic etch profile. The p-MOS 1100 b also comprises asource 1102 b, a drain 1104 b, and a gate 1106 b. However, the p-MOS1100 b comprises only a single layer of SiGe 1108 b (i.e., singlelattice) that forms the source 1102 b, drain 1104 b, as well as a fullreplacement channel 1110 b.

FIG. 12 illustrates a flow diagram of some embodiments of a conventionalmethod 1200 for manufacturing a strain inducing or high mobilitychannel. Note that the method 1200 is applicable in both the Hi-K metalgate last (HKL) flow as well as the Hi-K metal gate first (HKF) flow.While method 1200 is illustrated and described below as a series of actsor events, it will be appreciated that the illustrated ordering of suchacts or events are not to be interpreted in a limiting sense. Forexample, some acts may occur in different orders and/or concurrentlywith other acts or events apart from those illustrated and/or describedherein. In addition, not all illustrated acts may be required toimplement one or more aspects or embodiments of the description herein.Further, one or more of the acts depicted herein may be carried out inone or more separate acts and/or phases.

At step 1202 a substrate is provided. The substrate may comprise a 300mm or 450 mm crystalline wafer comprising silicon that has been dopedwith boron, phosphorus, arsenic, or antimony.

At step 1204 an active area is formed, which may comprise doping of thesubstrate.

At step 1206 a strain or high mobility layer is formed in a channelregion within the active area.

At step 1208 a gate is formed. The gate may comprise a layer ofPoly-Silicon above a layer of gate dielectric, and subjects thesubstrate to thermal processing (Hi T).

At step 1210 a lightly-doped drain (LDD) is formed to improve chargecarrier movement from the source to the drain. Formation of the LDDsubjects the substrate to thermal processing (Hi T). The thermalprocessing may comprise a plurality of high temperature anneals, aplurality of high temperature process steps, or a combination thereof.

At step 1212 a source and drain epi layer is formed. The source anddrain epi layer may comprise a layer of epitaxial SiGe for a p-MOS(e.g., SiGe_(0.3)), or a composite layer of epitaxial Si on layer ofepitaxial SiGe for an n-MOS (e.g., Si/SiGe_(0.2)). Formation of thesource and drain epi layer subjects the substrate to thermal processing(Hi T). The thermal processing may comprise a plurality of hightemperature anneals, a plurality of high temperature process steps, or acombination thereof.

At step 1214 a source and drain implant and anneal is performed. Thesource and drain implant may comprise an ion implantation of arsenic toimprove threshold voltage, and subjects the substrate to thermal cycling(Hi T). The thermal processing may comprise a plurality of hightemperature anneals, a plurality of high temperature process steps, or acombination thereof.

FIG. 13 illustrates a flow diagram of some embodiments of a method 1300for manufacturing a replacement channel that can be used for both apartial replacement channel and a full replacement channel. Note thatthe method 1300 is applicable in both the Hi-K metal gate last (HKL)flow as well as the Hi-K metal gate first (HKF) flow. While method 1300is illustrated and described below as a series of acts or events, itwill be appreciated that the illustrated ordering of such acts or eventsare not to be interpreted in a limiting sense. For example, some actsmay occur in different orders and/or concurrently with other acts orevents apart from those illustrated and/or described herein. Inaddition, not all illustrated acts may be required to implement one ormore aspects or embodiments of the description herein. Further, one ormore of the acts depicted herein may be carried out in one or moreseparate acts and/or phases.

At step 1302 a substrate is provided. The substrate may comprise a 300mm or 450 mm crystalline wafer comprising silicon that has been dopedwith boron, phosphorus, arsenic, or antimony.

At step 1304 an active area is formed, which may comprise doping of thesubstrate.

At step 1306 a sacrificial layer is formed in a channel region withinthe active area. The sacrificial layer may comprise a layer of epitaxialSiGe for a p-MOS (e.g., SiGe_(0.3)), or a composite layer of epitaxialSi on layer of epitaxial SiGe for an n-MOS (e.g., Si/SiGe_(0.2)).

At step 1308 a gate dielectric is formed, which may comprise SiO₂ or aHi-K dielectric to reduce power loss due to gate current leakage intothe channel region.

At step 1310 a gate material is formed. The gate may comprise a layer ofPoly-Silicon or metal above the layer of gate dielectric and subjectsthe substrate to thermal cycling (Hi T).

At step 1312 a gate spacer is formed, which may comprise a dielectricsidewall spacer to insure electrical isolation of the gate poly.

At step 1314 a lightly-doped drain (LDD) is formed to improve chargecarrier movement within the channel region.

At step 1316 a LDD anneal is performed to further improve charge carriermovement through the channel region. At the same time a dummy spacer isformed. Both processes subject the substrate to thermal cycling (Hi T).

At step 1318 the sacrificial layer is removed to form a recess by a wetchemical etch, a dry chemical etch, or a combination thereof, thatutilizes an isotropic etch profile.

At step 1320 a strain inducing layer or high mobility layer is formed inthe recess. The strain inducing layer or high mobility layer maycomprise a layer of epitaxial SiGe for a p-MOS (e.g., SiGe_(0.3)), agradient concentration layer (e.g., Ge), a doped layer (e.g., Boron orPhosphorus), a composite layer of epitaxial Si on layer of epitaxialSiGe for an n-MOS (e.g., Si/SiGe_(0.2)), or any combination thereof.

FIG. 14 illustrates a flow diagram of some embodiments of a method 1400for manufacturing a channel-last replacement channel. Note that themethod 1400 is applicable only in the Hi-K metal gate last (HKL) flow.While method 1400 is illustrated and described below as a series of actsor events, it will be appreciated that the illustrated ordering of suchacts or events are not to be interpreted in a limiting sense. Forexample, some acts may occur in different orders and/or concurrentlywith other acts or events apart from those illustrated and/or describedherein. In addition, not all illustrated acts may be required toimplement one or more aspects or embodiments of the description herein.Further, one or more of the acts depicted herein may be carried out inone or more separate acts and/or phases.

At step 1402 a substrate is provided. The substrate may comprise a 300mm or 450 mm crystalline wafer comprising silicon that has been dopedwith boron, phosphorus, arsenic, or antimony.

At step 1404 an active area is formed, which may comprise doping of thesubstrate.

At step 1406 a sacrificial layer is formed in a channel region withinthe active area. The sacrificial layer may comprise a layer of epitaxialSiGe for a p-MOS (e.g., SiGe_(0.3)), or a composite layer of epitaxialSi on layer of epitaxial SiGe for an n-MOS (e.g., Si/SiGe_(0.2)).

At step 1408 a dummy gate liner (IL) is formed.

At step 1410 a dummy gate material is formed. The dummy gate maycomprise a layer of dummy oxide beneath a dummy gate material (e.g.,Poly-Silicon). The dummy gate is capped by a hard mask. The formation ofthe dummy gate subjects the substrate to thermal cycling (Hi T).

At step 1412 a gate spacer is formed, which may comprise a dielectricsidewall spacer to insure electrical isolation of the gate poly.

At step 1414 a lightly-doped drain (LDD) is formed to improve chargecarrier movement within the channel region.

At step 1416 a LDD anneal is performed to further improve charge carriermovement within the channel region. The LDD anneal subjects thesubstrate to thermal cycling (Hi T).

At step 1418 a source and drain epi layer is formed. The source anddrain epi layer may comprise a layer of epitaxial SiGe for a p-MOS(e.g., SiGe_(0.3)), or a composite layer of epitaxial Si on layer ofepitaxial SiGe for an n-MOS (e.g., Si/SiGe_(0.2)).

At step 1420 a source and drain implant and anneal is performed. Thesource and drain implant may comprise an ion implantation of arsenic toimprove threshold voltage. The anneal subjects the substrate to thermalcycling (Hi T).

At step 1422 the hard mask is removed from above the gate, which maycomprise a wet chemical etch, a dry chemical etch, or a combinationthereof.

At step 1424 a contact etch stop layer is added above the gate, spacer,source, and drain. An interlayer dielectric (ILD) is added above theetch stop layer.

At step 1426 the contact etch stop layer and ILD are subjected to achemical-mechanical polish (CMP) to expose the top of the dummy gatematerial.

At step 1428 the dummy gate material is removed, which may comprise awet chemical etch, a dry chemical etch, or a combination thereof.

At step 1430 the dummy oxide is removed, which may comprise a wetchemical etch, a dry chemical etch, or a combination thereof.

At step 1432 the channel region is removed to form a recess. The removalof the channel region may comprise wet chemical etch, a dry chemicaletch, or a combination thereof, that utilizes an isotropic etch profile,and anisotropic etch profile, a sigma-shape etch profile, or atriangular etch profile.

At step 1434 a strain inducing layer or high mobility layer is formed inthe recess. The second strain inducing layer or high mobility layer maycomprise a layer of epitaxial SiGe for a p-MOS (e.g., SiGe_(0.3)), agradient concentration layer (e.g., Ge), a doped layer (e.g., Boron orPhosphorus), a composite layer of epitaxial Si on layer of epitaxialSiGe for an n-MOS (e.g., Si/SiGe_(0.2)), or any combination thereof.

FIG. 15 a-FIG. 15 f illustrate cross-sectional views of some embodimentsof channel-last replacement channel profiles. FIG. 15 a illustrates across-sectional view of some embodiments 1500 a of a sigma-shape profile1502 a for a channel-last replacement channel. FIG. 15 b illustrates across-sectional view of some embodiments 1500 b of a sigma-shape profile1502 b for a channel-last replacement channel. FIG. 15 c illustrates across-sectional view of some embodiments 1500 c of an anisotropicprofile 1502 c for a channel-last replacement channel. FIG. 15 dillustrates a cross-sectional view of some embodiments 1500 d of anisotropic profile 1502 d for a channel-last replacement channel. FIG. 15e illustrates a cross-sectional view of some embodiments 1500 e of atriangular profile 1502 e for a channel-last replacement channel. FIG.15 f illustrates a cross-sectional view of some embodiments 1500 f of atrapezoidal profile 1502 f for a channel-last replacement channel.

It will also be appreciated that equivalent alterations and/ormodifications may occur to one of ordinary skill in the art based upon areading and/or understanding of the specification and annexed drawings.The disclosure herein includes all such modifications and alterationsand is generally not intended to be limited thereby. In addition, whilea particular feature or aspect may have been disclosed with respect toonly one of several implementations, such feature or aspect may becombined with one or more other features and/or aspects of otherimplementations as may be desired. Furthermore, to the extent that theterms “includes”, “having”, “has”, “with”, and/or variants thereof areused herein; such terms are intended to be inclusive in meaning—like“comprising.” Also, “exemplary” is merely meant to mean an example,rather than the best. It is also to be appreciated that features, layersand/or elements depicted herein are illustrated with particulardimensions and/or orientations relative to one another for purposes ofsimplicity and ease of understanding, and that the actual dimensionsand/or orientations may differ substantially from that illustratedherein.

Therefore, the present disclosure relates to a device and method forstrain inducing or high mobility channel replacement in a semiconductordevice. The semiconductor device is configured to control current from asource to a drain through a channel region by use of a gate. Asacrificial layer is formed early in the semiconductor deviceprocessing. After one or more thermal processing steps are carried outwith the sacrificial layer in place, the sacrificial layer is removed toform a recess. A strain inducing or high mobility layer then fills therecess to insure a robust crystal structure with minimal defects. Straininducing or high mobility channel replacement may result in betterdevice performance compared to conventional techniques for straininducing channel formation, and is fully compatible with the currentsemiconductor manufacturing infrastructure.

In some embodiments, the strain inducing or high mobility channelreplacement comprises a partial replacement channel on a field effecttransistor (FET), wherein a sacrificial layer forming a source, drain,and channel region are removed after a series of thermal processingsteps to form a recess. The recess is then with a strain inducing orhigh mobility layer. These embodiments comprise a partially removing thesacrificial layer such that a portion of the sacrificial layer remainsimmediately below the gate. This results in a partial replacementchannel that is a combination of the sacrificial layer and the straininducing or high mobility layer.

In some embodiments, the strain inducing channel replacement comprises afull replacement channel on a field effect transistor (FET), wherein asacrificial layer forming a source, drain, and channel region areremoved after a series of thermal processing steps to form a recess. Therecess is then with a strain inducing or high mobility layer. Theseembodiments comprise a fully removing the sacrificial layer such thatnone of the sacrificial layer remains above the source, drain, andchannel region. This results in a full replacement channel comprisingonly the strain inducing or high mobility layer.

In some embodiments the present disclosure relates to a method forstrain inducing or high mobility channel replacement comprisingpartially replacing a channel on a field effect transistor (FET),wherein a sacrificial layer forms a source, drain, and channel region.After a series of thermal processing steps are performed, thesacrificial layer is removed to form a recess. The recess is then filledwith a strain inducing or high mobility layer. In the method of theseembodiments the sacrificial layer is partially removed such that aportion of the sacrificial layer remains immediately below the gate. Theremoved portion of the sacrificial layer is then replaced with a straininducing or high mobility layer such that the replacement channel is acombination of the sacrificial layer and the strain inducing or highmobility layer.

In some embodiments the present disclosure relates to a method forstrain inducing channel replacement comprising fully replacing a channelon a field effect transistor (FET), wherein a sacrificial layer forms asource, drain, and channel region. After a series of thermal processingsteps are performed, the sacrificial layer is removed to form a recess.The recess is then filled with a strain inducing or high mobility layer.In the method of these embodiments the sacrificial layer is fullyremoved such that none of the sacrificial layer remains above thesource, drain, and channel region. The removed sacrificial layer is thenreplaced with a strain inducing or high mobility layer such that thereplacement channel comprises only the strain inducing or high mobilitylayer.

What is claimed is:
 1. A method for fabricating a semiconductor device,comprising: providing a substrate; forming an active area within thesubstrate; forming a source and a drain within the active area; forminga channel region within the active area between the source and drain;forming a sacrificial layer within the source, drain, and channelregion; forming a gate above the channel region; removing thesacrificial layer to form a recess within the source, drain, and channelregion; and forming a strain inducing or high mobility layer in therecess, wherein the strain inducing or high mobility layer is configuredto provide increased charge carrier mobility in the channel region. 2.The method of claim 1, wherein the recess spans a region within theactive area under the gate continuously between the source and drain. 3.The method of claim 1, wherein a portion of the sacrificial layerremains above the recess and immediately below the gate.
 4. The methodof claim 1, wherein the sacrificial layer is fully removed such that agate dielectric abuts the recess.
 5. The method of claim 1, wherein thegate is removed from above the channel region prior to the forming thestrain inducing or high mobility layer in the recess.
 6. The method ofclaim 1, wherein removing the sacrificial layer comprises performing awet chemical etch, a dry chemical etch, or a combination thereof afterone or more thermal processing steps have been performed with thesacrificial layer in place.
 7. The method of claim 1, wherein formingthe strain inducing or high mobility layer comprises growing the straininducing or high mobility layer epitaxially on the substrate.
 8. Themethod of claim 1, wherein the sacrificial layer or the strain inducingor high mobility layer comprises SiGe, Ge, or Si on SiGe.
 9. A methodfor fabricating a semiconductor device, comprising: providing asubstrate; forming an active area within the substrate; forming a sourceand a drain within the active area; forming a channel region within theactive area between the source and drain; forming a sacrificial layerwithin the source, drain, and channel region; forming a gate dielectricabove the channel region; forming a gate material above the gatedielectric; subjecting the substrate to thermal cycling while thesacrificial layer is in place; after thermal cycling, removing thesacrificial layer from within the source, drain, and channel region toform a recess; and forming a strain inducing or high mobility layer inthe recess.
 10. The method of claim 9, wherein a portion of thesacrificial layer remains above the recess and immediately below thegate.
 11. The method of claim 9, wherein the sacrificial layer is fullyremoved such that a gate dielectric abuts the recess.
 12. The method ofclaim 9, wherein the gate is removed from above the channel region priorto the forming the strain inducing or high mobility layer in the recess.13. The method of claim 9, wherein removing the sacrificial layercomprises performing a wet chemical etch, a dry chemical etch, or acombination thereof, after one or more thermal processing steps havebeen performed with the sacrificial layer in place.
 14. The method ofclaim 9, wherein forming the strain inducing or high mobility layercomprises growing the strain inducing or high mobility layer epitaxiallyon the substrate.
 15. The method of claim 9, wherein the sacrificiallayer or the strain inducing or high mobility layer comprises SiGe, Ge,or Si on SiGe.
 16. A semiconductor device, comprising: an active area; acontinuous strain inducing or high mobility layer formed in the activearea and configured to provide increased charge carrier mobility; asource formed in the strain inducing or high mobility layer that emitscharge carriers; a drain formed in the strain inducing or high mobilitylayer that receives charge carriers from the source; a channel regionformed in the strain inducing or high mobility layer between the sourceand drain through which charge carriers flow from the source to thedrain; and a gate electrically coupled to a voltage source that controlsthe flow of charge carriers in the channel region.
 17. The semiconductordevice of claim 16, wherein the continuous strain inducing or highmobility layer comprises a single crystal.
 18. The semiconductor deviceof claim 17, wherein the continuous strain inducing or high mobilitylayer comprises a single SiGe or Ge crystal which is epitaxially grownon a Si substrate.
 19. The semiconductor device of claim 17, wherein thecontinuous strain inducing or high mobility layer comprises a single Sicrystal which is epitaxially grown on a single SiGe crystal which isepitaxially grown a Si substrate.
 20. The semiconductor device of claim16 comprising a planar field effect transistor (FET) or a fin fieldeffect transistor (finFET).